A signal processing device is configured to compensate for process and temperature variations deviating from a nominal process and temperature condition. A transconductance amplifier circuit produces a current output dependent on a voltage input and a transconductance gain. A transimpedance amplifier circuit produces a voltage output dependent on the current. A bias circuit comprises transistors (M.sub.1, M.sub.2) configured such that the gate and drain of the first transistor (M.sub.1) are connected to the gate of the second transistor (M.sub.2) and to a PTAT current source. The source of the first transistor (M.sub.1) is connected to a node via a first resistor (R.sub.1), and the source of the second transistor (M.sub.2) is connected to that node via a second, trimmable resistor (R.sub.2). A feedback circuit for the transimpedance amplifier comprises a third, trimmable resistor (R.sub.3). The ratio between a resistance of the second and third resistors (R.sub.2, R.sub.3) is constant.

This application describes apparatus and method for transimpedance gain control. A transimpedance amplifier circuit is described with a transimpedance amplifier having an input node for receiving an input current. A variable shunt resistance is connected to the input node and a controller is operable to controllably vary an open-loop transimpedance gain of the transimpedance amplifier and also the resistance of the variable shunt resistance so as to vary a closed-loop transimpedance gain of the transimpedance amplifier.

In some implementations, an automatic gain control (AGC) circuit comprises: a pre-divider circuit operable to pre-divide an input signal according to a pre-divider circuit setting and output a pre-divided signal; a pre-amplifier operable to pre-amplify the pre-divided signal and output a pre-amplified signal; a post-divider circuit operable to post-divide the pre-amplified signal according to a post-divider circuit setting; an analog-to-digital converter (ADC) operable to generate a digital data stream from the post-divided signal; logic operable to sample the digital data stream; determine a pre-divider circuit setting and a post-divider circuit setting based on the sampled data stream; set the pre-divider circuit and the post-divider circuit based on the determined settings; and generate a received signal strength value based on the pre-divider circuit setting and the post-divider circuit setting.

Methods and systems for accurate gain adjustment of a transimpedance amplifier using a dual replica and servo loop is disclosed and may include, in a transimpedance amplifier (TIA) circuit comprising a first TIA, a second TIA, and a third TIA, each comprising a configurable feedback impedance, and a control loop, where the control loop comprises a gain stage with inputs coupled to outputs of the first and second TIAs and an output coupled to the configurable feedback impedance of the second and third TIAs: configuring a gain level of the first TIA by configuring its feedback impedance, configuring a gain level of the third TIA by configuring a reference current applied to an input of the first TIA, and amplifying a received electrical signal to generate an output voltage utilizing the third TIA. The reference current may generate a reference voltage at one of the inputs of the gain stage.

A switched capacitor amplifier circuit includes an operational amplifier, a first capacitor and a second capacitor each having one end connected to a negative input terminal of the operational amplifier, a first switching circuit configured to connect the other end of the first capacitor and a signal source during a first operation, a second switching circuit configured to connect the other end of the second capacitor and the output terminal of the operational amplifier so as to connect the output terminal and the negative input terminal of the operational amplifier through the second capacitor during the second operation, and an impedance converter circuit configured to convert an output impedance of the signal source into a specified impedance, the impedance converter circuit being connected between the first switching circuit and the other end of the first capacitor.

An imaging system includes an array of photodetectors and electronic circuitry associated with the photodetectors to read intensity values from the photodetectors. The electronic circuitry can include an integrator with an integrator capacitor having a nominal capacitance, wherein a gain of the electronic circuitry associated with a photodetector can depend at least in part on the actual capacitance of the integrator capacitor, the actual capacitance differing from the nominal capacitance. The imaging system can be configured to determine a gain factor that depends at least in part on the actual capacitance and/or a signal voltage input to the integrator. The imaging system can be configured to apply the gain factor based at least in part on the actual capacitance of the integrator capacitor calculated. The imaging system can be a thermal imaging system and may include an infrared camera core.

A front-end amplifier circuit for receiving a biological signal includes a signal channel. The signal channel amplifies the biological signal to generate a detection current and includes a capacitive-coupled transconductance amplifier. The capacitive-coupled transconductance amplifier amplifies the biological signal with a transconductance gain to generate a first current.

In part, aspects of the invention relate to methods, apparatus, and systems for intensity and/or pattern line noise reduction in a data collection system such as an optical coherence tomography system that uses an electromagnetic radiation source and interferometric principles. In one embodiment, the noise is intensity noise or line pattern noise and the source is a laser such as a swept laser. One or more attenuators responsive to one or more control signals can be used in conjunction with an analog or digital feedback network in one embodiment.

Introduced here are techniques for implementing a comparator-based LIDAR system with improved components, such as an improved high-speed comparator circuit, to acquire depth information from the surroundings of an unmanned moving object (e.g., a UAV). In various embodiments, the LIDAR system includes an amplifier module with different configurations of anti-saturation circuitry. The LIDAR system may further include various feedback control mechanisms for noise interference reduction and timing measurement compensation including, for example, dynamic gain adjustment of the photodetector module, and/or dynamic adjustment of comparators' thresholds. Among other components, the disclosed comparator circuit can provide the LIDAR system with a wide dynamic range, preventing large signal amplification saturation while also providing sufficient magnification of small signals.

A photoionization detector sensor equipped with an adjustable gain amplifier, and method of standardizing output of the photoionization detector sensor by adjusting the gain so that an actual test value expected to produce a known anticipated value matches the anticipated value.